Switches are widely used in systems. For example, the Serial Rapid Input Output (sRIO) Gen2 Switch may be used to meet wireless infrastructure customer's requirements for WCDMA/LTE Base Stations.
Some of these requirements are challenging, for example, an 18-port Serial Rapid IO (sRIO) Gen2 Switch may be required to achieve very high performance (up to 360 Gbit) with minimum packet latency (<30 ns excluding sRIO protocol stack delay) to meet wireless infrastructure customer's requirements for WCDMA/LTE Base Stations.
A switch needs to be able to deal with packets of varying sizes and meet bandwidth and latency requirements. Switch packet forwarding can be packet based arbitration or credit based arbitration. Packet based arbitration can only achieve bandwidth fairness with fixed size packets but not for variable size packets. Credit based arbitration can achieve bandwidth fairness with variable size packets but it can penalize high priority traffic and miss the required latency if prior occurred lower priority traffic has consumed all its credit. This presents a problem.